Sanaa, Yemen (CNN) -- Four Yemeni soldiers were killed and three others wounded Wednesday in ongoing clashes between the country's military and suspected al Qaeda militants in southern Yemen, the military said.
Yemen has launched a wide-scale offensive against al Qaeda in the region.
A government official said Tuesday the offensive in Shabwa province was in response to a militant attack last week on a pipeline carrying liquefied natural gas. The official described the multibillion-dollar pipeline as the "lifeline of the region."
The official asked for anonymity because he is not authorized to speak to the media.
A senior U.S. defense official said the U.S. military has been providing intelligence, surveillance and reconnaissance help during the offensive but stressed that Yemeni forces were primarily responsible for its planning and execution.
"The Yemeni government understands the threat within its own borders, to themselves and their people," the defense official said.
A key United Nations humanitarian agency raised an alarm about the violence Wednesday.
"Together with other U.N. agencies, UNICEF has expressed our concern to the Yemen Government about the possible humanitarian impact in and around Shabwa province due to military intervention in the area," the agency's representative in Yemen, Geert Cappelaere, told CNN.
U.N. agencies are moving food, water purification materials and other humanitarian supplies nearby "in anticipation of possible humanitarian need," Cappelaere said.
The Yemeni government has been fighting a growing al Qaeda element in Yemen called al Qaeda in the Arabian Peninsula. The militant offshoot group grabbed the attention of the West with the attempted bombing of a Northwest Airlines trans-Atlantic flight as it landed in Detroit, Michigan, on December 25.
The suspect, Umar Farouk AbdulMutallab, who has pleaded not guilty to six federal terrorism charges, was reportedly trained and armed in Yemen.
Since its inception in January 2009, al Qaeda in the Arabian Peninsula has claimed responsibility for numerous terrorist attacks against Saudi, Korean, Yemeni and U.S. targets.
Yemen put on trial four al Qaeda suspects Monday. Yemen's defense ministry website said the suspects -- two Yemenis, a German and an Iraqi -- stand accused of criminal conspiracy and planning to target foreign tourists and interests as well as vital government and military installations in Yemen.
Al Qaeda in the Arabian Peninsula leader and Muslim cleric Anwar al-Awlaki, a U.S. citizen who is believed to have prepared AbdulMutallab for his operation, remains at large.
A second government official in Yemen said he believes that al-Awlaki is probably in Shabwa, but stressed that the operation was not developed as a means to capture him.
"Ninety-five percent of Yemen and its government believe Awlaki is in Shabwa Province. I hope he is captured, but from what I've heard from officials, there is a lot of conflicting information at this point, and I don't believe he is surrounded right now," the source said.
The Obama administration has stepped up its attention on Yemen, and on Monday, the president's counterterrorism adviser, John Brennan, affirmed U.S. military support with Yemeni President Ali Abdullah Saleh, the U.S. Embassy said.
A counterterrorism official said the administration recognizes that "not enough is being done in Yemen" to meet the growing challenge posed by al Qaeda in the Arabian Peninsula.
"We need to scale up efforts to disrupt the group," said the official, who spoke about sensitive issues on the condition of anonymity.
The official said that conditions in Yemen have allowed al Qaeda to regroup there and that all options to fight the Arabian Peninsula group are under review at the White House.
The Obama administration is considering adding armed CIA drones to help fight the increasing threat of al Qaeda in Yemen, a U.S. official said last month.
CNN's Gena Somra contributed to this report.